Apparatus for feeding paperboard blanks

ABSTRACT

An improved blank feeding machine for feeding successive bottom blanks from a stack of blanks into adjacent processing machinery comprises a support table for supporting the stack of blanks thereon and defines with a gate an opening therebetween through which the bottom blanks are successively advanced into the adjacent machinery; a suction box reciprocating beneath the blanks applies suction pressure to the bottom blanks from the beginning of the feed stroke of the suction box throughout substantially the first half of the feed stroke and thereafter vents the suction pressure to atmosphere until the beginning of the next successive feed stroke. A suction pump delivers suction pressure to the suction box during the forward stroke of a piston within the suction pump; the suction pump includes a valve operable upon command to prevent delivery of the suction pressure to the suction box. A selectively operable first command system operates the valve to prevent delivery of suction pressure during each forward stroke of the piston to prevent advancement of the blanks during a &#39;&#39;&#39;&#39;stop-feed&#39;&#39;&#39;&#39; mode; a selectively operable second command system operates the valve to prevent delivery of suction pressure during alternate forward strokes of the piston to prevent advancement of the blanks during alternate feed strokes of the suction box during a &#39;&#39;&#39;&#39;skip-feed&#39;&#39;&#39;&#39; mode of operation.

United States Patent Kuehn APPARATUS FOR FEEDING PAPERBOARD Primary Examiner-Evon C. Blunk Assistant E.raminerBruce H. Stoner, Jr.

Attorney, Agent, or FirmBoyce C. Dent; Oscar B. Brumback [57] ABSTRACT An improved blank feeding machine for feeding successive bottom blanks from a stack of blanks into adjacent processing machinery comprises a support table for supporting the stack of blanks thereon and defines with a gate an opening therebetween through which the bottom blanks are successively advanced into the adjacent machinery; a suction box reciprocating beneath the blanks applies suction pressure to the bottom blanks from the beginning of the feed stroke of the suction box throughout substantially the first half of the feed stroke and thereafter vents the suction pressure to atmosphere until the beginning of the next successive feed stroke. A suction pump delivers suction pressure to the suction box during the forward stroke of a piston within the suction pump; the suction pump includes a valve operable upon command to prevent delivery of the suction pressure to the suction box. A selectively operable first command system operates the valve to prevent delivery of suction pressure during each forward stroke of the piston to prevent advancement of the blanks during a stop-feed" mode; a selectively operable second command system operates the valve to prevent delivery of suction pressure during alternate forward strokes of the piston to prevent advancement of the blanks during alternate feed strokes of the suction box during a "skip-feed" mode of operation.

7 Claims, 9 Drawing Figures PATENTEDSEP 91975 3,904,190

SHEET 2 0F 1 FIG. 3 FIG. 4

APPARATUS FOR FEEDING PAPERBOARD BLANKS BACKGROUND OF THE INVENTION 1. Field of the invention This invention relates generally to sheet feeding or delivering apparatus having a pneumatic bottom feed mechanism for feeding the bottom-most blank of a stack of paperboard blanks into a processing mechanism.

2. Description of Prior Art Suction feeders for feeding the bottom blank from a stack of paperboard blanks are well known in the art and are used for feeding the blanks into an adjacent processing apparatus.

One type of suction feeder utilizes a stationary suction chamber such as shown in Ward, ct al. US. Pat. No. 3588.095 and Thayer U.S. Pat. No. 3,754,752. Such suction feeders are designed to hold the bottom blank against the support table. A reciprocating feed bar engages the trailing edge of the bottom blank and moves it through a gate mechanism into a processing apparatus These suction feeders utilize the reciprocating feed bar to move the bottom blank through the gate mechanism and were developed to eliminate the prob lem of feeding warped blanks which prevent them from passing through the gate mechanism. These suction feeders generally do their job very well. The suction chamber pulls the warped bottom blank against the support. table and the suction pressure is strong enough to flatten the warped blank and allow the feeder bar to engage the trailing edge of the blank and move it through the gap in the gate mechanism.

Although the reciprocating feed bar type suction feeder has the above-mentioned advantage, it does have a number of disadvantages. First, the suction pressure in the suction chamber must be continuously applied so that the warped blank will stay flat during movement through the gate mechanism. This continu ous suction pressure creates friction between the blank and support table which the feeder bar must overcome to advance the blank. The feeder bar pushes the trailing edge of the blank and tends to bend and deform the trailing edge thus damaging the product,

A second disadvantage is that the feeder bar moves rapidly in the area where the machine operator stands at the rear of the stack. As he loads the stack on the support table. his hands are in close proximity to the feeder bar. Should the operator be careless or make a mistake, his hand may contact the moving feeder bar and injure his hands.

Another example of a suction feeder is shown in E.L. Bishop US. Pat. No. 2,331,533 and T.D. Bishop US. Pat. No. 3.126,](l8. which is an improvement over the EL. Bishop Patent. in this type of suction feeder, the suction box itself reciprocates along the plane of the feed table eliminating the need for a feeder bar and consequently. the disadvantages associated with a feeder bar. Suction in the box draws the bottom blank downward into flat contact with the top of suction box. The suction box moves the blank forward until its leading edge is gripped by a pair of pull rollers beyond the gate which pull the blank into the processing machine. When the pull rolls grip the blank, the vacuum in the suction box is released to the atmosphere which releases the blank from the suction box and allows easy pulling of the blank by the pull rollers. The suction box then moves rearward until it is below the next bottom blank at which time vacuum is reapplied to the suction box to feed the next blank.

It is desirable at times to stop the feeding of the blanks into the processing apparatus without having to shut down the machinery or to feed a blank on every other stroke of the suction box. To stop the feeding of the blanks in the foregoing feeder, vacuum is not ap plied to the suction box when the suction box is at the beginning of its feed stroke, thus. the suction box will not pick up the blank as it moves forward on each stroke. This is referred to as stop-feed. To feed a blank on every other forward stroke of the suction box, vacuum is only applied to the suction box at the beginning of every other forward stroke, thus moving a blank only on every other stroke. This is referred to as skipfeed.

To produce the stopfeed and skip-feed functions in suction feeders utilizing a reciprocating suction box, the vacuum supply to the suction box must be cut off at the appropriate time. Normally. a conventional suction pump is used in which a piston therein reciprocates in timed sequence with the suction box to provide suction pressure during a suction stroke of the piston. It is arranged to shut off the vacuum to the suction box altogether in the stop fecd mode or system of operation and shut off the vacuum to the suction box on every other forward stroke in the skip-feed mode of operation. In the past, this has been accomplished by mechanically controlling a valve mechanism on the suction pump. In the stop-feed mode. the valve is left open so that when the piston moves forward on its suction stroke, the piston chamber is vented to atmosphere and thus no vacuum or suction is created. in the skipfeed mode. the valve is mechanically opened on every other forward suction stroke of the piston and closed on the remaining alternate forward strokes; thus, vacuum is only created on the forward stroke of the piston when the valve is closed.

To open and close the valve, it has been the practice to use a complex mechanical lever and dual cam arrangement which is connected to the valve to open and close it. To select the stop-feed mode, the operator moves a lever to the stop-feed position. This rotates a cam shaft carrying a lobed disc cam which contacts the valve upon rotation of the camshaft to maintain the valve in an open position as long as the cam engages the valve.

To select the skip-feed mode. the operator moves the lever to a skip-feed position and a second lobed disc cam, carried on a camshaft rotating in timed rotation to the suction pump piston, contacts the valve to open it on the first forward stroke of the piston, Opening the valve, vents the suction pump cylinder so the piston cannot create vacuum during its forward stroke.

On the rearward stroke of the piston. the camshaft rotates the high lobed of the cam past the valve permit ting it to close. The configuration of the cam is arranged to keep the valve closed on the next forward stroke of the piston; thus, the piston can create a vacuum in the suction box. On the second rearward stroke, the camshaft again rotates the cam to open the valve and keeps it open on the next forward stroke of the piston, thus not supplying vacuum to the suction box. This is continued long as the skip-feed operation is desired.

Although this mechanical lever and cam arrangement produces the desired stop-feed and skip-feed functions. it does have a number of disadvantages. One disadvantage is the high cost of the mechanical cam arrangement. The materials and maintenance costs are extremely high and these costs are reflected in the purchase price of the entire suction feeder machine.

A second disadvantage is that the mechanical lever and cam mechanism has a large number of rotating parts subject to wear which require lubrication and maintenance from time to time which means the suction feeder apparatus must be shut down which results in loss of production time. In addition. because a large number of parts are involved. the reliability of the system is poor since mechanical parts tend to wear and break. thus necessitating the taking of the machine out of production for repairs.

A third disadvantage is that suction feeder machines are inherently noisy. One source of noise is the lever and cam mechanism on the suction feeder. The box making industry is continuously seeking ways to reduce noise. In addition. the Occupational Safety and Health Administration has set forth standards governing maximum noise levels in box plants; industry is required to meet these OSHA standards. As mentioned above. the mechanical lever and cam mechanism has been found to be the source of a great amount of noise resulting from the large number of movable and continuously contacting parts.

SUMMARY OF THE INVENTION Accordingly. an object of the present invention is to provide an improved blank feeding machine that will overcome the aforementioned disadvantages and others. Thus. this invention provides a blank feeding apparatus of the reciprocating suction box type that effectively reduces the noise output of the blank feeding machine by utilizing an automatic. nonnicchanical system for providing a skip-feed mode of operation and a stopfeed mode of operation.

This is generally accomplished by providing a blank feeding machine used for feeding successive bottom blanks from a stack of blanks into adjacent processing machinery with a support means for supporting the stack of blanks thereon and defining with a gate means an opening thcrebctween through which the bottom blanks are successively advanced into the adjacent machinery. An advancing means reciprocates beneath the bottom blank along the support plane of the support means and applies suction pressure to the bottom blanks from the beginning of its food stroke and contiw ues substantially through the first half of the feed stroke. Thereafter. suction pressure is vented to atmosphere until the beginning of the next successive feed stroke. A suction pump means delivers suction pressure to the advancing means during the forward stroke of a piston means within a suction pump means; the suction pump means includes a valve means operable upon command for preventing delivery of the suction pressure to the advancing means. A selectively operable first command means controls operation of the valve means to prevent delivery of suction pressure during each forward stroke of the piston means to prevent advancemcnt of the blanks during the stop-feed mode of operation. A selectively operable second command means controls operation of the valve means to prevent delivery of suction pressure during alternate forward strokes of the piston means to prevent advancement of the blanks during alternate feed strokes of the advancing means during the skip-feed mode of operation.

The above and further objects and novel features of the invention will appear more fully from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood. however. that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like parts are marked alike.

FIG. 1 is a schematic illustration in side elevation of the present invention showing the feeder generally and including the reciprocating suction box, the suction pump. and the valve mechanism for regulating the vacuum applied to the suction box;

FIG. 2 is a cross-sectional view of the blank feeding machine of FIG. I taken along the line II-II showing the lower pull rolls. suction box. and a vane switch arrangement;

FIG. 3 is an enlarged cross-sectional view ofthe valve assembly of FIG. 1 showing a pivotable plate mechanism and solenoid-activated plunger for pivoting the plate mechanism;

FIG. 4 is an end view of FIG. 3;

FIG. 5 is a cross-sectional view of the blank feeding machine of FIG. I taken along the line VV showing a cam arrangement for reciprocating the suction box of FIG. 1:

FIG. 6 is a side view of the cam arrangement of FIG. 5 taken along the lines of VIVI showing a cam track and cam follower;

FIG. 7 is a perspective view ofthe suction box of FIG. 1 showing a suction inlet and exhaust port arrangement;

FIG. 8 is an electrical schematic diagram showing the electrical arrangement for activating the valve mechanism of FIG. I in the STOP-FEED mode of operation; and

FIG. 9 is an electrical schematic diagram showing the electrical arrangement for activating the valve mechanism of FIG. 1 in the SKIP-FEED mode of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1. the invention generally comprises a blank feeding machine, denoted generally by numeral 10, for feeding successive bottom blanks 12 from a stack of blanks 14 into adjacent processing machinery, not shown. For illustration purposes. the present invention is shown as it is used in the corrugated box making industry. that is. the stack of blanks 14 of corrugated paperboard is fed by blank feeding machine 10 into adjacent corrugated paperboard processing machinery such as. for example. scoring and slotting apparatus. printing apparatus. and box making apparatus. It should be understood, however. that the present invention can be used in other type applications such as. for example cardboard processing. laminated board processing, or any other industry that feeds sheets of material from a stack of sheets.

Blank feeding machine I0 generally comprises a support table 16 for supporting the stack of blanks l4 thereon and defining with a conventional gate assembly 18 an opening 20 thcrebetween through which bottom blanks 12 are successively advanced into the adjacent machinery. A suction box. denoted generally by numeral 22, is reciprocable beneath stack 14 in a plane level with the top of table 16 and applies suction pressure to bottom blanks 12 from the beginning of the feed stroke of suction box 22 and continuing substantially through the first half of the feed strokev Thereafter the suction pressure is vented to atmosphere until the bcginning of the next successive feed stroke. A suction pump. denoted generally by numeral 24, is used for delivering suction pressure to suction box 22 during the forward stroke of a piston 26 within suction pump 24. Suction pump 24 includes a valve. denoted generally by numeral 28, operable upon command for preventing delivery of the suction pressure to suction box 22. A sc lcctiyely operable first command system switch. dcnoted generally by numeral 30. is used to operate valve 28 to prevent delivery of the suction pressure during each forward stroke of piston 26 to prevent advancement of bottom blanks 12. A selectively operable second command system switch. denoted generally by numeral 32. is used for operating valve 28 to prevent delivery of the suction pressure during alternate forward strokes of piston 26 to prevent advancement of bottom blanks 12 during alternate feed strokes of suction box 22.

For illustration purposes. it should be understood that when reference is made to the feed stroke of suction box 22 and the forward stroke of piston 26, it is meant that suction box 22 and piston 26 are moving from right to left as depicted in FIG. 1. Likewise it is to be understood that the return stroke of suction box 22 and the rearward stroke of piston 26 will be considcred as the movement from left to right. In addition. it is to be expressly understood that the term command means used in the specification and claims refers to an electrical, pneumatic. or hydraulic system as later explained and does not refer to any mechanical system as previously explained.

More specifically. and referring to FIG. 1. the blank feeding machine consists of a support table 16 which supports a stack of corrugated paperboard blanks 1-4. At the front of table 16, a gate assembly 18 is spaced above table 16 an amount substantially equal to the thickness of bottom blank 12. The stack of blanks 14 are placed upon table [6 so their leading edges 34 abut gate [8 and bottom blank 12 lies adjpcent to space betvt'ccn gate 18 and table 16, so that suction box 22 can engage blank 12 and. on the feed stroke of suction box 22, blank 12 is fed through space 20 to be picked up by a pair of feed rollers 36 and 38 which are adjacent space 20 and which are rotated by a drive system. not shown. in blank feeding machine 10. Upper feed roller 36 may be covered with rubber or a synthetic covering which gives a high co-efficient of friction so that when roller 36 grips blank 12, it will pull the blank through rollers 36 and 38 for feeding into adjacent processing machinery. Lower roller 38 may be made similar to upper roller 36 except it is preferably made of steel with longitudinal grooves 40, FIG. 2, for gripping the underside of blank 12. The Central portion of rollers 36 and 38 are gapped at 42, FIG. 1 and 2, so that the front nose 44 of suction box 22 can pass between rollers 36 and 38 so that blank 12, which is usu ally considerably wider than suction box 22, can be gripped by rollers 36 and 38.

Referring to FIGS. 1 and 2, a suction box support frame 43 surrounds lower roller 38 and is rigidly attached to a support frame. not shown. of blank feeding machine 10. The top 45 of support frame 43 is in horizontal alignment with suction chamber 54 of suction box 22 and provides a surface on which suction cham ber 54 is supported when suction box 22 is advanced on its feeding stroke into gap 42 between rollers 36 and 38.

Generally. a suction pump 24 is utilized to create a vacuum within suction box 22. The suction pressure within suction box 22 seizes the bottom blank 12 when suction box 22 is at the end of its return stroke. that is when the top of suction box 22 is completely beneath blank 12. The suction box is advanced through space 20 at a gradually increasing speed. Its maximum velocity is arranged to coincide with the peripheral velocity of rollers 36 and 38. When blank 12 is brought into cngagement with rollers 36 and 38, this velocity is maintained for a substantially short distance to allow time for the vacuum in box 22 to be vented to atmosphere which returns suction box 22 to atmospheric pressure to release blank 12. The vacuum is maintained in suction box 22 during the feed stroke toward feed rollers 36 and 38, but once the leading edge 34 of blank 12 has been successfully engaged by feed rollers 36 and 38, the vacuum in suction box 22 is cut off and brought to atmospheric pressure as quickly as possible so that suction box 22 does not hold blank 12 for any more time then is required for rollers 36 and 38 to grip blank 12. This is generally accomplished by cutting off the vacuum to suction box 22 and then venting it to atmosphere as will be later described.

Referring now to FIGS. 1 and 7. suction box 22 com sists of a box-likc body 46 which is mounted beneath table 16 on support members 48 which are secured to the frame. not shown. of blank feeding machine 10. A hollow tube. denoted generally by numeral 50. is slidably mounted within a bore 52 of body 46. The forward part of tube is secured to a suction chamber 54 such as by bolting a flange 56 on suction chamber 54 to a ilangc 58 on tube 50 by bolts 60 and 62. Suction chamber 54 has atop member 63 which is substantially rectangular in shape and is secured to a top portion of suction box 54 such as by bolts, not shown. Top member 63 has a plurality of openings 64 which extend into suction chamber 54 so that suction pressure may be applied to blank 12. Suction chamber 54 is positioned within a slot 66 centrally located in table 16 so that suction chamber 54 will be able to grip the central forward portion of blank 12.

Tube 50 consists of a hollow tubular member 68 which is attached to suction chamber 54 by flange 58 as previously described. A hollow central portion 70 is open to suction chamber 54 as shown in FIG. 1. Tubular member 68 includes an opening 72 with a sealing member 74 inserted at the rearward portion of opening 72 and completely contacting the inner periphery of central portion 70 and abutting a shoulder portion 76. Sealing member 74 is held against shoulder portion 76 by bolt 78 thus sealing the rear portion of tube 50 from the front part of tube 50.

Referring to FIGS. 1, 5 and 6, tube 50 is reciproeated forwardly and rearwardly within bore 52 of body 46 by a lever, denoted generally by numeral 80. Lever 80 includes three legs of which one leg 82 is connected to the rearward portion of tube 50 by a linking bar 84 which is connected to tube by pin 86. A second leg 88 is pivotably connected to frame support 48 by bracket 90. Legs 82 and 88 are allowed to pivot about bar 84 and bracket 90 by pivot pins 92. A third leg 94 is connected to a cam mechanism 96 by a pin 98 and a cam follower 100 which rides in a cam track 102 in cam mechanism 96. The cam mechanism 96 propells lever 80 forwardly and rearwardly at the correct speed and positive movement required for proper feeding of blank I2 by suction box 22.

Referring to FIGS. 1 and 7. box like body 46 includes a forward sealing element 104 which is secured to a forward part of body 46 such as by bolts. not shown. in order to prevent dust and other foreign particles from getting between tube 50 and body 46 when tube 50 moves into and out of body 46. Body 46 has a port I06 extending through body 46 and when tube 50 is at its rearward most position. opening 72 registers with port 106. Port I06 connects with suction pump 24 by a flexible conduit I08 so that suction chamber 54 can be subjected to vacuum. When tube 50 moves forward. opening 72 remains in contact with port I06 for a predetermined interval. Opening 72 is then completely disconnected from port 106 when opening 72 passes through region 110 of body 46 which has no port. The forward speed of suction chamber 54 is increased until it reaches the peripheral speed of rollers 36 and 38, then opening 72 registers with a second port 112 in body 46 which is connected to atmosphere. When opening 72 registers with second port 112, suction chamber 54 is rapidly vented to atmosphere thereby releasing blank 12 for continuing advancement by feed rollers 36 and 38.

For ease of illustration. port 72 in tube 50 and ports I06 and [12 in body 46 have been shown in a vertical position. Although the ports 72. 106, and II2 may be positioned anywhere that is desired, the preferred position is the horizontal setting as shown in FIG. 7.

Referring now to FIGS. 1. 2, 3, 4, and 5. suction pump 2-4 consists of a cylinder I14 having a port 116 that opens into an opening 118 in a sleeve I20 that fits around cylinder I I4 and abuts a shoulder 122 on cylinder 4. A second sleeve I24 surrounds cylinder I14 abutting sleeve I20 and holding sleeve in its correct position on cylinder I14. Flexible conduit 108 is connected to port I IS. A piston 26 is reciprocally slideable within cylinder I14. A connecting rod 126 is pivotally connected at one end to piston 26 and extends through an opening in the forward portion of piston 26 and through an opening in the forward end of cylinder I I4 where connecting rod 126 pivotably connects with a rotatable plate I28. A drive shaft I30 extending perpendicular to the travel of connecting rod 126 passes through the center of plate I28 and is rigidly connected thereto. One end of shaft I30 is connected to cam mechanism 96 and the other end is connected to the drive system. not shown. for feeding machine 10 such as by gear I32. A housing I34 surrounds plate I28 and part of shaft I30. One end of housing 134 is slidcably engagcable with the forward end of cylinder 114 in order to maintain the interior portions of pump 24 free from foreign matter and to maintain lubricants therein. As previously mentioned. shaft connects with piston 26 and cam mechanism 96. Cam track I02 is profiled so that when shaft 130 rotates in the direction to make piston 26 move in the forward direction, lever 80 will. at a predetermined time, propel suction box 22 on its feed stroke and when piston 26 moves rearwardly. suction box 22 moves on its return stroke. Cam track I02 is additionally profiled to increase the speed of suction box 22 in its feed stroke until suction box 22 reaches its maximum forward velocity just before it reaches its maximum forward position at which time its forward velocity is substantially the same as the peripheral velocity of rollers 36 and 38 so that there is a smooth transition of blank 12 from suction box 22 to rollers 36 and 38.

At the rearward end of cylinder I14 is valve mechanism 28 which consists of a plate 136. FIGS. I, 3, and 4, which is secured to the end of cylinder I14 such as by bolts, not shown. Plate I36 has an opening 138 extending into cylinder I14. Surrounding opening 138 is a washer 140 which is secured to plate I36 such as by screws. not shown. Washer 140 is preferably made from a resilient material such as. for example. rubber or the like. An arm mechanism 142 is pivotally connected to plate I36 by bracket I44 and pin I46. One arm 148 of arm mechanism 142 extends vertically parallel to opening 138. At the end of arm I48 is a perpendicularly extending protrusion 150. Protrusion I50 extends toward opening I38. A circular plate 152 having an outer diameter greater than the diameter of opening 138 is connected to protrusion at substantially its center by bolt 154 and nut I56. Arm 148 is so positioncd that when arm mechanism 142 pivots down ward. plate I52 contacts washer I40, thereby closing opening 138. A second arm 158 extends perpendicular to arm I48 and has an opening I60 extending there through. Surrounding valve 28 is a housing I62 which is secured to cylinder I14 such as by welding. An opening 164 in top 166 of housing I62 is in vertical alignment with opening I60 in arm I58. A hollow sleeve 168 is secured in opening I64 such as by threading. A collar I70 surrounds sleeve I68 so that a portion of sleeve I68 extends below collar 170. Collar 170 is secured to sleeve I68 such as by welding. A biasing member such as a coil spring I72 is positioned around the bottom portion of sleeve 168 so that its end abuts collar 170. The other end of spring I72 is positioned over opening 160 in arm 158. If desired, a recess may be formed around opening I60 and spring I72 placed therein so that spring I72 will not slide on arm 158. Spring 172 is positioned so it is in partial compression so spring 172 will pivot arm mechanism 142 to place plate I52 in contact with washer I40 when no other forces are acting on arm mechanism 142.

An actuator mechanism. denoted generally by numeral 174, is positioned on top I66 of housing 162 in vertical alignment with opening 164. FIGS. I, 3 and 4 illustrate actuator I74 as an electrically activated solenoid I76 and plunger mechanism. Although the preferred actuator is shown as a solenoid I76, other actuators such as. for example. a pneumatically operated piston and cylinder system or a hydraulically operated piston and cylinder system may be utilized.

Actuator mechanism I74 comprises a plurality of spaced vertically extending support members 178 secured to top 166 such as by welding. A pair of cross members 180 span the distance between adjacent support members 178 and are secured thereto by bolts I82. Solenoid 176 is supported by support plate I84 and is secured to cross members I80 such as by bolts, not shown.

A resilient cushion 186 having an opening in alignment with opening 164 surrounds opening 164 and is secured to top 166.

Solenoid 176 contains a plunger 188 that moves upward in the vertical plane into solenoid 176 when solenoid 176 is energized. When not energized, plunger 188 seats upon cushion 186. A rod 190 is connected to the base of plunger 188 and extends through opening 164, sleeve 168, spring 172, and opening 160 in arm 158. A collar 192 of larger diameter than opening 160 surrounds rod 190 and abuts the underside of arm 158. The bottom of rod 190 is threaded and collar 192 is held in place by threading a nut 194 on the end of rod 192. Nut 194 is only threaded on rod 190 to a pointjust before arm mechanism 142 begins to pivot upward. This is to insure that plate 152 will remain in contact with washer 140 as long as solenoid 176 is de energized.

When piston 26 moves in its forward stroke, valve 28 is in the closed position, that is, plate 152 is in contact with washer 140 closing opening 138, thus as piston 26 moves forward a vacuum is created in a space 115 in cylinder 114. The vacuum continues to build up in space 115 until piston 26 passes and opens port 116 which substantially instantaniously creates a vacuum within suction chamber 54 since opening 72 in tube 50 is over port 106 in body 46. At this time suction box 22 grips blank 12 by suction pressure and suction box 22 moves on its feed stroke while piston 26 continues its forward stroke. After suction box 22 releases blank 12 as previously described, suction box 22 moves on its return stroke and piston 26 moves rcarwardly. As piston 26 covers port 116 and moves toward plate 136, pressure is built up in space 115 since the volume of space 115 is decreasing. This pressure pushes on plate 152 pivoting arm mechanism 142 and compressing spring 172. As arm mechanism 142 pivots, plate 152 moves away from washer 140 allowing the air under pressure in space 115 in cylinder 114 to escape through opening 138. When piston 26 reaches its maximum rearward position the pressure build-up ceases and spring 172 pivots arm mechanism 142 so that plate 152 again contacts washer 140 and closes opening 138.

In the continuous feeding mode of operation of feeding mechanism 10. the above-described arrangement is all that is needed, On every feed stroke of suction box 22, vacuum is applied by suction pump 24 to suction box 22 which feeds blank 12 and when suction box 22 reaches its maximum velocity, the vacuum is vented to atmosphere which releases blank 12 to the control of rolls 36 and 38. Suction box 22 then returns to its starting position while piston 26 in suction pump 24 moves rearwardly until it is ready to reapply the vacuum to suction box 22 on the next feed stroke.

As previously described. it is desirable in many instances to stop feeding blanks at any given time without shutting down the equipment or to feed blanks only on every other feed stroke of the suction box. It is therefore desirable to allow the machine operator to command the blank feeding machine to stop feeding blanks in response to malfunctions or other reasons or to feed blanks only on alternate feed strokes to permit feeding of blanks ofcxtra length as will be understood by those skilled in the art.

The preferred type ofcommand system is of the elcc trical type as shown in FIGS. 1, 2. 8. and 9. Although the electrical command system is preferred, other systems such as pneumatic or hydraulic may be used ifdc sired by substantially substituting the proper pneumatic or hydraulic components for the electrical components shown in FIGS. 8 and 9.

Referring to FIGS. 1 and 2, the electrical command system includes a control panel 196 with a first command system switch 30. marked FEED/STOP in FIG. 1, which. when depressed, signals blank feeding machine 10 to stop feeding blanks and a second command system switch 32. marked FEED/SKIP in FIG. 1, which, when depressed, signals blank feeding machine 10 to feed blanks on alternate feed strokes of suction box 22.

An electrical switch, denoted generally by numeral 198, FIGS. 1 and 2 is connected electrically to control panel 196 by wires 200. As shown in FIGS. 1 and 2, switch 198 is preferably of a conventional magnetic vane type limit switch; however, other types of switches may also be used. A conventional l 15 volt alternating current vane type limit switch may be purchased from the General Electric Corporation under model number CR1 15A12. Vane type switch 198 consists of a contact assembly 202 having a slot 204 extending through the body. Contact assembly 202 also contains a pair of contacts, not shown, in which one of the contacts is moveable and magnetized. Contact assembly 202 is prcfcrrably mounted on support frame 43 such as by bolts, not shown, in a position substantially below and substantially rearward of lower roller 38 as shown in FIG. 1. Slot 204 extends parallel to the direction of motion on suction box 22. A vane member 206 con structed from metal such as iron or steel is secured to suction box 22. Vane 206 is constructed in the shape of an L so that one leg 208 is secured to flange 58 of tube by bolts 60 and nut 62. The other leg 210 extends pcrpcndicular to leg 208 and in alignment with slot 204 in contact assembly 202. Arm 210 is made of sufficient length so that when suction box 22 moves forward on its feed stroke, arm 210 will pass through slot 204 as suction box 22 reaches its maximum forward position. When arm 210 enters slot 204, the magnetized contact is attracted to arm 210 but remains stationary in a normally closed position. As arm 210 moves rearward when suction box 22 is on its return stroke, the magnetized Contact also moves rearward opening the normally closed contacts.

Although the above is the preferred arrangement for switch 198, switch 198 may be positioned anywhere there are parts moving in timed sequence with the suction box 22. For example, contact assembly 202 may be positioned near arm 82 of lever and vane 206 may be mounted on arm 82 so that when arm 82 reciprocates, vane 206 passes through slot 204.

Control panel 196 is electrically connected to solenoid 176 by wires 212 (FIG. 1) so that upon command and when piston 26 is on its rearward stroke, solenoid 176 is energized which causes plunger 188 to raise rod 190 and since rod 190 is prevented from passing through opening in arm 158 by collar 192 and nut 194. arm mechanism 142 pivots around pivot pin 146 to the position shown by the dotted lines in FIG. 3. Solenoid 176 is only activated on the rearward or exhaust stroke of piston 26 because if solenoid 176 is activated on the forward stroke of piston 26, that is the vacuum stroke, the solenoid would. have to overcome the vac uum pressure to pivot arm mechanism 142 which may cause damage to solenoid 176. When arm mechanism 142 is pivoted. plate 152 no longer contacts washer 140 and cylinder 114 is thereby vented to atmosphere. Arm mechanism 142 will remain pivoted and thus valve mechanism 28 will be in the open position as long as solenoid 176 remains energized. When solenoid 176 is de-encrgized on command, plunger 188 drops on resilicnt cushion 186 and spring 172. being in compression. pivots arm mechanism 142 until plate 152 contacts washer 140, thus closing opening 138.

FIGS. 8 and 9 illustrate the electrical schematic for energizing solenoid 176 in both the first and second command systems respectively. The operations shown in FIGS. 8 and 9 will be described in detail during the explanation of the operation of blank feeding machine 10.

OPERATION Referring first to the mode of operation wherein a bottom blank 12 is fed into adjacent processing machincry on each forward or feed stroke of suction box 22, the machine operator obtains a stack of corrugated box blanks 14 and places them on table 16 so that the leading edges 34 of the blanks in stack 14 abut gate 18. The bottom blank 12 is adjacent to and in alignment with space 20 between table 16 and gate 18. The machine operator pulls out switches 30 and 32 on control panel 196 which starts blank feeding machine in operation. that is. it starts rollers 36 and 38 rotating and starts drive shaft 130 rotating.

For illustration purposes. it will be assumed that at the start of operations. piston 26 is at its most rearward position and suction box 22 is at the end of its return stroke so that suction chamber 54 is directly beneath bottom blank 12'. however. it should be understood that piston 26 and suction box 22 may be in any position when starting blank feeding machine 10 in operation. As drive shaft 130 rotates clockwise, plate 128 is also rotated clockwise and since connecting rod 126 is con neeted to plate 128 and piston 26, piston 26 begins its forward stroke. Since plate 152 of arm mechanism 28 is in contact with washer 140 and covering opening 138 in cylinder 114. the forward stroke of piston 26 creates a vacuum within space 115 in cylinder 114. As piston 26 moves forward. drive shaft 130 also rotates cam mechanism 96. but because of the profile of cam track [02, lever 80 does not move and cam track 102 just moves around cam follower 100. As piston 26 continues on its forward stroke it uncovers port 116 in cylinder 114. When port 116 is uncovered the high vacuum in space 115 in cylinder 114 causes a vacuum to be substantially instantaneously created in suction chamber 54 since there is, at this moment. an open path from space 1 through port 116, port 118, flexible conduit 108. port 106 in body 46, port 72 in ram 50, hollow space 70 in tube 50, and the opening between tube 50 and suction chamber 54 to openings 64 in plate 63. The vacuum in suction chamber 54 causes bottom blank 12 to be held on top of plate 63 by the suction pressure.

When bottom blank 12 is held by the suction pressure, the cam track 102 profile is such that upon further rotation of drive shaft 130 and cam mechanism 96. lever 80 propels tube 50 forward and consequently propels suction chamber 54 on its feed stroke at an ever increasing velocity. At the same time. piston 26 continues on its forward stroke. As tube 50 moves forward. suction pressure continues to be applied to blank 12 as long as opening 72 is in alignment with opening 106. As

opening 72 passes over region on body 46, vacuum is discontinued since opening 72 is no longer in alignment with opening 106. At this moment in time, nose 44 of suction chamber 54 enters gap 42 between rollers 36 and 38 and suction box 22 is moving forward at substantially the same velocity as the peripheral velocity of rollers 36 and 38. Suction chamber 54 continues forward for a substantially short distance until rollers 36 and 38 have gripped blank 12. At this moment in time. opening 72 becomes aligned with opening 112 in body 46 which is vented to atmosphere and the vacuum still remaining in suction chamber 54 is also vented to atmosphere releasing the suction pressure on blank 12 thus releasing the grip that suction chamber 54 had on blank 12. At this moment. the profile of cam track 102 is such that piston 26 is at its maximum forward position. Upon further clockwise rotation of drive shaft 130. piston 26 moves rearwardly and lever 80 changes direction and pulls tube 50 and suction chamber 54 on their return stroke. Rollers 36 and 38 are now free to feed blank 12 into adjacent processing machinery without any retarding forces by suction box 22.

As tube 50 and suction chamber 54 move on their return stroke. piston 26 also moves rearwardly and covers opening 116 in cylinder 114. As piston 26 continues to move rearwardly. the air within space in cylinder 114 is compressed since the volume within space 115 is continuously decreasing, causing pressure to build up. The pressure acts upon plate 152 of arm mechanism 142, and when the pressure is strong enough to overcome the biasing force of spring 172, arm mechanism 142 is pivoted about pin 146 so that plate 152 no longer contacts washer and allows opening 138 to be open to atmosphere. The air pressure in space 115 is then allowed to escape through opening 138 and piston 26 can continue on its rearward stroke without any pressure build-up. Once piston 26 reaches its most rearward position. the pressure created by piston 26 rearward movement ceases and spring 172 pivots arm mechanism 142 downward until plate 152 contacts washer 140 and closes opening 138. When piston 26 reaches its most rearward position. tube 50 and suction chamber 54 are at the end of their return stroke so suction chamber 54 is beneath the next bottom blank 12.

The next feed stroke of suction box 22 is ready to begin in the same manner as described above. The blank feeding machine 10 continues to feed blanks 12 on each feed stroke in the manner described until the operator desires to command blank feeding machine 10 to stop feeding bottom blanks 12 altogether or to command blank feeding machine 10 to only feed blanks 12 on every other feed stroke of suction box 22.

FIGS. 8 and 9 show the preferred electrical system to command blank feeding machine 10 to stop feeding bottom blanks 12 (FIG. 8) or to skip feed bottom blanks 12 (F10. 9). F105. 8 and 9 illustrate the electrical configuration of the control circuits when blank feeding machine 10 is feeding a bottom blank 12 on every feed stroke of suction box 22. In this configurw tion FEED/STOP button 30 and FEED/SKIP button 32 are in the pulled out position and consequently solenoid 176 is dc-energized. For ease of illustration. F108. 8 and 9 are shown separately but. in actual operation. leads 300 are connected to the same conventional power source and leads 302 are connected to ground.

Referring to FIGS. 8 and 9, for the continuous feed ing operation. relay 304 is energized and switch 314A is open; relay 306 is energized and switch 306A is closed and contact 3068 is closed; relay 308 is deenergizcd and contact 308A is closed and contacts 308B. 308C. and 308D are open; relay 310 is ale-- energi/ed and contacts 310A. 3108 and 310C are open; main feeding machine 10 contact 312 is closed; relay 314 is deaenergized and contact 314A is open and relay 316 is tie-energized and contacts 316A and 316D are open and contacts 31613 and 316C are closed. The skip feed circuit also contains a flip-flop relay denoted generally by numeral 318. Flipflop relay 318 has a pair of input relays 320 and 322 and a pair of output relays 324 and 326. Flip-flop relay 318 is dis-energized and contact 320A is open. contact 322A is closed. contacts 324A and 32415 are open. and contact 326A is closed. Therefore the only electrical path that is complete for continuous feeding of blank 12 is through contacts 308A. 3068, and relay 304 and through main feeding machine 10 contact 312 and relay 306, thus bypassing solenoid 176.

When it is desired to stop feeding blanks 12 alto gethcr the machine operator depresses FEED/STOP iutton 30 and makes contact at point 301. For illustration purposes, it will be assumed that the machine operator depresses the stop button when suction box 22 is on its feed stroke so that the contacts in vane switch 198 are closed. Relay 308 is energized which opens contact 308A and closes contacts 308B. 308C. and 308D. The closing of contact 3081) creates a path through transformer 332 to vane switch 198 and ener gizcs relay 316 through the closed contacts in vane switch 198 which opens contact 316C and closes contact 316A. The energizing of relay 316 allows the suction box 22 to continue its feed stroke until blank 12 is picked up by rollers 36 and 38. and delays activation of solenoid 176 until the return stroke of suction box 22 and piston 26 so that solenoid 176 is not energized to pivot arm mechanism 142 during the vacuum stroke. When suction box 22 is on its return stroke, vane limit switch 198 opens. due to the vane on suction box 22 pulling the movable magnetized contact away from the stationary COfllZLiCl. Although the time when the contacts in vane switch 198 open can be at any time during the return strokes of suction box 22 and piston 26. the preferred time is substantially between 10 and 25 after piston 26 starts its rearward stroke in order to insure that solenoid 176 is not energized while piston 26 is on its vacuum creating stroke. This de-energizes relay 316 and opens contact 316A and closes contact 3166. Since contact 308C and 316C are both closed, relay 310 is energized closing contacts 310A, 3108, and 3106. This provides a path through contacts 3108 and 308B to maintain relay 310 energized and since relay 310 is now continuously energized. there is a path through switch 306A and contact 310A to solenoid 1 76,

When contact 310A closes. solenoid 176 is energized which pulls plunger 188 (FlGS. 1, 3, and 4) up into solenoid 176. This pulls up rod 1.90 which pivots arm mechanism 142 to the position shown by the dotted lines in FIG. 3. The arm mechanism 142 will remain pivoted and opening 138 will remain uncovered as long as solenoid 176 remains energized. Therefore. on the forward stroke ofpiston 26, opening 138 remains open and no vacuum is created in space 1 15. \Nhen opening 116 is uncovered. no vacuum will be applied to suction chamber 54 and suction chamber 54 will not pick up bottom blank 12. Thus. suction box 22 will move on its feed stroke without moving blank 12 and this operation will continue long as FEED/STOP button 30 is depressed. Solenoid 176 will remain energized even though the contacts in vane switch 198 are continuing to close and open thereby energizing and de energizing relay 316 which in turn keeps opening and closing contacts 316A and 316C because there remains a complete current path to keep relay 310 energized through contacts 3108 and 3088, thus insuring that contact 310A remains closed.

When continuous feeding of blank 12 is again desired the machine operator pulls out FEED/STOP button 30 which breaks the contact at point 301. This de energizes relay 308 and opens contacts 308B. 308C. and 3081) and closes contact 308A. When contact 3085 opens, it breaks the current path to relay 310 by way of contacts 31013 and 30813 and when contact 308C opens it breaks the path to relay 310 by way of contacts 308C and 316( when relay 316 is energized but because it is undesirable to deenergizc solenoid 176 when suction boy 22 and piston 26 are on their for ward strokes. there is still a path to relay 310 by way of contacts 3108 and 316A when vane switch 198 contacts are closed. When suction box 22 is on its return stroke the contacts in vane switch 198 open, decncrgizing relay 316 and opening contact 316A and closing contact 316C This breaks the last remaining path to relay 310. thus Lie-energizing relay 310 and opening contacts 310A. 3108 and 310C.

The opening of contact 310C breaks the path to vane switch 198 which keeps relay 316 de-energizcd; opening of contact 3108 breaks the path to relay 310; and the opening of contact 310A breaks the path to solenoid 176. This tie-energizes solenoid 176 which allows plunger 188 to drop onto cushion 186 and drop rod 190 downward which allows spring 172 to pivot arm mechanism 142 so that plate 152 covers opening 138 and on the next forward stroke of piston 26 vacuum will be created in space 115 so vacuum can be applied to suction chamber 54 for subsequent feeding of bot tom blank 12.

When it is desired to skip l'eed blank 12, that is. feed blanks 12 on every other feed stroke of suction box 22, the machine operator depresses FEE D/SKIP botton 32 which makes contact at points 328 and 330. This pro vides a current path through transformer 332 to vane switch 198. For illustration purposes. it will be assumed that suction box 22 has just started its feed stroke for feeding blank 12 when the operator depresses the FEED/SKIP button 32. Since the contacts in vane switch 198 are closed, relay 316 is energized thereby closing contact 316D and opening contact 3168. The closing of contact 316D energizes relay 320 through closed contact 326A. When relay 320 is energized, contact 320A is closed and contact 322 A is opened. After suction box 22 feeds blank 12 into rollers 36 and 38 it starts its return stroke. Substantially 10 to 25 de grees after piston 26 has started its return stroke. vane 210 passing through slot 204 in contact assembly 202 opens the contacts in vane switch 198 and tie-energizes relay 316. This opens contact 3161) and closes contact 3168. Since contact 320A is closed. relay 324 is energized which opens contact 326A and closes contacts 324A and 3248. As vane 210 leaves slot 204 in Contact assembly 202 on the return stroke of suction box 22. the contacts in vane switch 198 close thereby energizing relay 3l6 which closes contact 316D and opens contact 3168. There is now a current path through contacts 316D and 324A to relay 322. This energizes relay 322 which opens contact 320A and closes contact 322A. There is a second path through contact 3248 to relay 314. This energizes relay 3l4 which closes contact 314A thereby creating a path to energize solenoid 176. Since suction box 22 is on its return stroke. solenoid 176, being energized, pivots arm mechanism 142 and opens opening 138. When suction box 22 starts its next feed stroke and piston 26 starts its next forward stroke, opening 138 remains opened since solenoid 176 is still energized and piston 26 does not create a vacuum and thus no vacuum is applied to suction chamber 54 and the bottom blank 12 is not gripped by suction chamber 54 and no blank is fed on the forward stroke. As suction box 22 starts its return stroke, the contacts in vane switch 198 open, de-energizing relay 3l6 which opens contact 316D and closes contact 3l6B. This energizes relay 326 which opens contacts 324A and 324B and closes contact 326A. The opening of contact 3248. de-encrgizes relay 314 which opens contact 314A. The opening of contact 314A dc energizes solenoid 176, releasing plunger [88, and rod 190 so that spring 172 can pivot arm mechanism l42 when piston 26 has reached its maximum return stroke.

As vane 210 leaves slot 204 on the return stroke of suction box 22, the contacts in vane switch 198 close thereby energizing relay 316 which closes contact 316D and opens contact 3168. Since solenoid I76 is not energized. piston 26 will create a vacuum within space US which will apply a vacuum to suction cham ber 54 so that on this feed stroke. bottom blank 12 will be gripped by suction pressure and fed to rollers 36 and 38 by suction box 22. The above-described cycle will continue to repeat as long as the FEED/SKIP button 32 is depressed and will continue to feed blanks 12 only on alternate feed strokes of suction box 22.

When the machine operator desires to stop the skip feed operation and return to the regular feed operation, he pulls out FEED/SKIP button 32 which breaks contact at points 328 and 330. This breaks the path to vane switch 198 and to relay 314. Since relay 314 can no longer be energized contact 314A cannot be closed and thus solenoid [76 cannot be energized.

The foregoing has presented a novel blank feeding machine. The problem and danger of having a recipro eating feed bar to feed each bottom blank has been eliminated by having a reciprocating suction box apply suction pressure to the bottom blank on the suction boxs feed stroke. In addition by having a reciprocating suction box feed each blank and then release the blank by venting the suction to atmosphere, no friction must be overcome when rolls 36 and 38 pull the blank from the suction box.

The problems associated with mechanically operating a valve mechanism to allow the blank feeding machine to stop feeding blanks or to feed blanks only on every other feed stroke of the suction box have been eliminated by using and electrically operable command system for actuating the valve mechanism.

Accordingly, the invention having been described in its best embodiment and mode of operation, that which is desired to be claimed by Letters Patent is:

1. An improved blank feeding machine for feeding successive bottom blanks from a stack of blanks into adjacent processing machinery comprising in combination:

support means for supporting said stack of blanks thereon and defining with a gate means an opening therebetween through which said bottom blanks are successively advanced into said adjacent machinery;

advancing means reciprocable beneath said stack for applying suction pressure to said bottom blanks from the beginning of the feed stroke of said advancing means and continuing substantially through the first half of said feed stroke and thereafter for venting said suction pressure to atmosphere until the beginning of the next successive feed stroke;

suction pump means for delivering suction pressure to said advancing means during the forward stroke ofa piston means within said suction pump means. said suction pump means including valve means electrically operable upon command for preventing delivery of said suction pressure to said advancing means;

selectively operable first command means for electrically operating said valve means to prevent delivcry of said suction pressure during each forward stroke of said piston means to prevent advancement of said blanks; and

selectively operable second command means for electrically operating said valve means to prevent delivery of said suction pressure during alternate forward strokes of said piston means to prevent advancement of said blanks during alternate feed strokes of said advancing means.

2. The blank feeding machine of claim 1 wherein said valve means opens automatically in response to an increase in air pressure ahead of said piston means during the return stroke thereof for venting said suction pump means and closes automatically in response to a biasing means connected thereto during the forward stroke of said piston means.

3. An improved suction pump means for a blank feeder comprising in combination:

a cylinder means;

a piston means reciprocable within said cylinder means for creating suction pressure within said cylinder means on the forward stroke of said piston means;

drive means connecting said piston means and said blank feeder for reciprocating said piston means in timed relation thereto;

conduit means connected between said cylinder means and a reciprocable blank advancing means on said blank feeder adapted to deliver suction pressure of predetermined magnitude from said cylinder means substantially instantaneously to said advancing means at the beginning of the feed stroke of said advancing means; and

a valve means for automatically venting said cylinder means during the return stroke of said piston means, said valve means being electrically operable in response to a first command means to continuously vent said cylinder means to atmosphere on each forward stroke of said piston means and electrically operable in response to a second command means to vent said cylinder means to atmosphere on alternate forward strokes of said piston means 4. The suction pump means of claim 3 wherein said electrically operable valve means comprises:

a valve plate means on said cylinder means pivotable into closing engagement with a vent means in said cylinder means.

resilient biasing means for pivoting said valve plate means into closing engagement during forward strokes ofsaid piston means. said valve plate means being pivotable out of closing engagement with said vent means during return strokes of said piston means for venting said cylinder means to utmosphcrc'. and

actuator means for pivoting said valve plate means out of closing engagement in opposition to said biasing means during forward strokes of said piston means in response to signals from said first and second command means.

5. The suction pump means of claim 4 wherein said actuator means comprises an electrically energized solenoid means mounted to said cylinder means for pivoting said valve plate means out of closing engagement in response to electrical signals from said first and second command means.

6. The suction pump means of claim 3 wherein:

said first and second command means include first electrical switch means energized by said blank feeder for producing an electrical signal in timed relation thereto;

said first command means further includes a second switch means for activating said valve means in response to said electrical signals to pivot said valve means to an open position on the rearward strokes of said piston means and to maintain said valve means in said open position during subsequent forward strokes of said piston means; and

said second command means further includes a second switch means for activating said valve means in response to said electrical signals to pivot said valve means to said open position on alternate rearward strokes of said piston means and to maintain said valve means in said open position on said alternate forward strokes of said piston means.

7. The suction pump means of claim 6 wherein: said second switch means of both of said first and second command means includes an electrical switching means for activating said valve means. 

1. An improved blank feeding machine for feeding successive bottom blanks from a stack of blanks into adjacent processing machinery comprising in combination: support means for supporting said stack of blanks thereon and defining with a gate means an opening therebetween through which said bottom blanks are successively advanced into said adjacent machinery; advancing means reciprocable beneath said stack for applying suction pressure to said bottom blanks from the beginning of the feed stroke of said advancing means and continuing substantially through the first half of said feed stroke and thereafter for venting said suction pressure to atmosphere until the beginning of the next successive feed stroke; suction pump means for delivering suction pressure to said advancing means during the forward stroke of a piston means within said suction pump means, said suction pump means including valve means electrically operable upon command for preventing delivery of said suction pressure to said advancing means; selectively operable first command means for electrically operating said valve means to prevent delivery of said suction pressure during each forward stroke of said piston means to prevent advancement of said blanks; and selectively operable second command means for electrically operating said valve means to prevent delivery of said suction pressure during alternate forward strokes of said piston means to prevent advancement of said blanks during alternate feed strokes of said advancing means.
 2. The blank feeding machine of claim 1 wherein said valve means opens automatically in response to an increase in air pressure ahead of said piston means during the return stroke thereof for venting said suction pump means and closes automatically in response to a biasing means connected thereto during the forward stroke of said piston means.
 3. An improved suction pump means for a blank feeder comprising in combination: a cylinder means; a piston means reciprocable within said cylinder means for creating suction pressure within said cylinder means on the forward stroke of said piston means; drive means connecting said piston means and said blank feeder for reciprocating said piston means in timed relation thereto; conduit means connected between said cylinder means and a reciprocable blank advancing means on said blank feeder adapted to deliver suction pressure of predetermined magnitude from said cylinder means substantially instantaneously to said advancing means at the beginning of the feed stroke of said advancing means; and a valve means for automatiCally venting said cylinder means during the return stroke of said piston means, said valve means being electrically operable in response to a first command means to continuously vent said cylinder means to atmosphere on each forward stroke of said piston means and electrically operable in response to a second command means to vent said cylinder means to atmosphere on alternate forward strokes of said piston means.
 4. The suction pump means of claim 3 wherein said electrically operable valve means comprises: a valve plate means on said cylinder means pivotable into closing engagement with a vent means in said cylinder means; resilient biasing means for pivoting said valve plate means into closing engagement during forward strokes of said piston means, said valve plate means being pivotable out of closing engagement with said vent means during return strokes of said piston means for venting said cylinder means to atmosphere; and actuator means for pivoting said valve plate means out of closing engagement in opposition to said biasing means during forward strokes of said piston means in response to signals from said first and second command means.
 5. The suction pump means of claim 4 wherein said actuator means comprises an electrically energized solenoid means mounted to said cylinder means for pivoting said valve plate means out of closing engagement in response to electrical signals from said first and second command means.
 6. The suction pump means of claim 3 wherein: said first and second command means include first electrical switch means energized by said blank feeder for producing an electrical signal in timed relation thereto; said first command means further includes a second switch means for activating said valve means in response to said electrical signals to pivot said valve means to an open position on the rearward strokes of said piston means and to maintain said valve means in said open position during subsequent forward strokes of said piston means; and said second command means further includes a second switch means for activating said valve means in response to said electrical signals to pivot said valve means to said open position on alternate rearward strokes of said piston means and to maintain said valve means in said open position on said alternate forward strokes of said piston means.
 7. The suction pump means of claim 6 wherein: said second switch means of both of said first and second command means includes an electrical switching means for activating said valve means. 